Can VSYS of nPM1304 be used to power a load?

[Tom.Fu]

Hi Support Team 

There is a chip needs 2.7~4.2V power supply, can VSYS of nPM1304 be used to power the chip? We originally planned to power this chip directly with a battery, but we are concerned that the accuracy of nPM1304 in measuring battery level and current. By the way, does VSYS have short circuit protection? Many thanks.

[Tharaka]

Hi 

Yes you can use nPM1304 VSYS to supply power to external circuitry.  There is no dedicated short circuit protection but there is battery discharge current limit IBATLIM of typical 210mA. If the system load exceeds the discharge current limit, VSYS voltage drops below VSYS_POF causing the device to reset, as described in POF — Power-fail comparator.

It is recommended to use a battery with internal protection (PCM) when using the nPM1304. 

Regards

Tharaka

[Tom.Fu]

Hi Tharaka

Does the voltage of nPM1304 VSYS follow the voltage of VBUS and VBAT? Can the voltage of nPM1304 VSYS be configure below 4.2V. Many thanks.

[Tharaka]

Hi 
Yes, VBUS voltage is seen at VSYS as a supply, if the VBUS voltage is within specified limits. VSYS follow VBAT when VBUS/USB is absent. 
The battery is isolated when VBUS is connected and the battery is fully charged. Under this condition, VBUS supplies VSYS. When VBUS is disconnected, CHARGER supplies VSYS from VBAT.

See these sections for more info : Dynamic power-path management , SYSREG — System regulator

Tharaka